3rd generation partnership project (3GPP) long term evolution (LTE) is an improved version of a universal mobile telecommunication system (UMTS) and is introduced as the 3GPP release 8. The 3GPP LTE uses orthogonal frequency division multiple access (OFDMA) in a downlink, and uses single carrier-frequency division multiple access (SC-FDMA) in an uplink. The 3GPP LTE employs multiple input multiple output (MIMO) having up to four antennas.
In 3GPP LTE, a resource block (RB) is used as a basic unit of resource allocation. The RB includes a plurality of subcarriers and a plurality of orthogonal frequency division multiplex (OFDM) symbols. The RB can be divided into a physical resource block (PRB) and a virtual resource block (VRB). According to a rule of mapping to the PRB, the VRB is divided again into a localized VRB (LVRB) and a distributed VRB (DVRB).
The VRB is used in resource allocation for downlink transmission or uplink transmission. In downlink transmission, a base station (BS) reports to a user equipment (UE) a specific VRB through which a downlink data packet is transmitted. In uplink transmission, the BS reports a specific VRB through which the UE transmits an uplink data packet.
A data transmission scheme can be divided into a frequency diversity scheduling (FDS) scheme which obtains a performance gain by using frequency diversity and a frequency selective scheduling (FSS) scheme which obtains a performance gain by using frequency selective scheduling.
In the FDS scheme, a transmitter transmits a data packet to subcarriers distributed in a frequency domain. That is, symbols in the data packet experiences channel fading in the frequency domain. By preventing all symbols in the data packet from experiencing unfavorable fading, reception performance is improved.
In the FSS scheme, the transmitter transmits a data packet by using one or a plurality of contiguous subcarriers in a favorable fading state in the frequency domain.
In a wireless communication system, a plurality of UEs are present in one cell, and a radio channel condition for each UE has a different characteristic. Therefore, even in the same subframe, one UE may need to use the FDS scheme and another UE may need to use the FSS scheme. Accordingly, it is necessary to design such that the FDS scheme and the FSS scheme can be multiplexed effectively in one subframe. The FSS scheme has a gain only when a band favored for the UE is selectively used in an overall band. On the other hand, the FDS scheme does not require selective transmission for a specific frequency band as long as a frequency interval capable of obtaining sufficient diversity is maintained, irrespective of whether the specific band is good or bad.
The FDS scheme uses the DVRB since data is transmitted by using subcarriers distributed in the frequency domain. The FSS scheme uses the LVRB since data is transmitted by using subcarriers contiguous in the frequency domain.
In recent years, there is an ongoing discussion on 3GPP LTE-advanced (LTE-A) that is an evolution of the 3GPP LTE. The 3GPP LTE-A ensures backward compatibility with the 3GPP LTE, and supports a wideband by using carrier aggregation.
It is difficult to apply a PRB-VRB mapping method in the conventional 3GPP LTE, which has a narrower band than that of the 3GPP LTE-A, directly to the wideband 3GPP LTE-A.